The joint venture between supermarket chain Tesco and O2 said that the tariff price a customer signs up to at the start of a contract will be the same price they pay for the entire duration of the contract.

Tesco Mobile also said that this "tariff promise" will come at "no additional cost" to the customer.

According to recent research by consumer group Which?, 70% of consumers in the UK had no idea that a mobile operator could increase prices during the contract period.

After estimating that network providers are increasing tariff costs by a median of 81p a month, Tesco mobile believes that UK consumers pay out £217 million extra on their phone bills in one year alone.

Tesco Mobile claims that it has never raised its pay-monthly tariff costs mid-contract, and now it wants to cement that promise.

"We believe it's only fair to stick to the contract that we make with our customers, and see no reason to change the core tariff price that a customer has signed up to," Simon Groves, the chief marketing officer of Tesco Mobile, said.

"We've never put our pay-monthly tariff prices up mid-contract and this tariff promise demonstrates our continued commitment to our customers.

"Being open and honest with them is incredibly important to us and we're proud to be setting an example of best in class mobile service."

Ernest Doku, telecoms expert at uSwitch.com, said that following EE's announcement of a fixed-price contract option, Tesco is arguably going "one step further" by offering assurances that all customers will be protected from price rises.

"By ensuring that all plans have a fixed price for their duration, it brings some much-needed clarity and reassurance," said Doku.